seems according to my pcm, that my psps is messed up, so i looked in my ,anuals and came up zilch aside from directing me to a mechanic...what the crap is that about? i would appreciate any info i can get since the haynes AND chiltons show me nada...
1990 f 150 5.0
thanks
eric

 

I "believe" the PSP switch uses a 5 volt reference, and only looks for a change in this reference to tell the PCM that the switch is open (pump being worked) or closed (not working). It's pretty much just a dummy signal as far as I can tell. Are you having problems, with your idle being affected by you turning the steering wheel? One of the steps when checking the codes is to swing the steering wheel back and forth to test the switch. Is this registering anything for ya?

 

i did the whole string of tests and got only 52, and yes it affects my idle somewhat significantly, when i crank it all the way to one side or the other it damn near dies, and under normal use i can see a strain, i did in fact do the steering wheel swing in the test

 

I'd try replacing the switch, once checking to ensure that all the wiring is intact and in good condition. I had a problem with mine doing a smiliar problem at idle, and after replacing the switch, it was cured. The switch was in the range of $30 and only available from the dealership. Try it, and hopefully it'll take care of your problems.

Luke

 

ok then...my last question, where in the heck is it? i cant seem to find it in my manuals

 

it should be mounted in-line on the Hi pressure line. On the part of the line that rises up.

 

On Monday I walked through all the electrical signals on the TFI side. I was satisfied when all systems acted properly. I was also getting a decent spark with the HEI tester. The only thing left was the injectors in my erratically acting 1993 F-150 5.0L. So I bought a set and installed and today I have very weak to no spark. This is my dilemma with this truck. The symptoms wander from day to day. The truck wouldn't start for many months and then suddenly started and ran well for one week, then died. After the latest go round I tested the PCM again with an OBD1 tester and the only fault is a code 52. I've had this fault for some time and was told it shows the switch to be open, which is what it should be when running. The test is done with KOEO. I'm at the end of my rope with this truck. New PCM, new TFI, new distributor, plugs, wires, sensors, etc. and now injectors. A Ford mechanic told me he's seen this with a temp sensor and also with bad injectors. Upon changing the injectors out I did observe several very wet intake runners, so I figured this may indicate stuck injectors and the black smoke and rich plugs when pulled. I did see a YouTube video where a temp sensor caused a no start situation. My sensors are new except for the power steering pump switch. Ford says this would not cause a no start condition.

Compression 150-160 lbs
fuel pressure 45 psi